Think kidneys in hypertension and managing the combination

The For Kidneys Sake podcast series is brought to you by Imperial College Healthcare NHS Trust and North West London Integrated Care Board (NWL NHS)

Could your patient's kidneys be telling you something their blood pressure isn't?

In this episode of For Kidney's Sake, Prof Jeremy Levy and Dr Andrew Frankel are joined by Prof Ian Wilkinson, President of the British and Irish Hypertension Society, to explore the close relationship between hypertension and chronic kidney disease (CKD). The discussion explains how the two conditions influence each other, why kidney assessment should form part of every hypertension diagnosis, and how clinicians can identify patients who may have secondary causes of hypertension or early kidney damage. The conversation focuses on practical steps for primary care, including the importance of measuring eGFR, urine ACR and performing urine dipstick testing as part of routine assessment.

The episode also examines treatment strategies that not only lower blood pressure but protect kidney function. The speakers discuss the role of ACE inhibitors and ARBs as kidney-protective therapies, the appropriate use of thiazide diuretics in CKD, selecting suitable second-line antihypertensive agents, blood pressure targets, monitoring schedules, accurate blood pressure measurement and lifestyle interventions. Throughout, the emphasis remains on treating the whole patient rather than simply targeting a blood pressure number, with practical advice aimed at improving long-term kidney and cardiovascular outcomes.

Top 5 Take aways: 

·  Hypertension and chronic kidney disease have a two-way relationship, each can contribute to the development and progression of the other. 

·  Every patient with hypertension should have kidney assessment including eGFR, urine ACR and urine dipstick testing. 

·  ACE inhibitors and ARBs are kidney-protective treatments and should be optimised where appropriate, even when blood pressure is already controlled. 

·  Thiazide diuretics remain effective in many patients with CKD and should not be avoided simply because kidney function is reduced. 

·  Accurate blood pressure measurement, lifestyle modification and good medication adherence are essential for protecting both cardiovascular and kidney health.

Resource Links:
NICE GUIDELINES [NG203] chronic kidney disease: assessment and management Overview | Chronic kidney disease: assessment and management | Guidance | NICE

Northwest London CKD guidelines for primary care Chronic kidney disease (nwlondonicb.nhs.uk)

The purpose of this podcast is to inform and educate health care professionals working in the primary care and community setting. The content is evidence based and consistent with NICE guidelines and North West Guidelines available at the time of publication.

The content of this podcast does not constitute medical advice and it is not intended to function as a substitute for a healthcare practitioner’s judgement.

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Transcript

Jeremy
hello everybody, I'm Jeremy Levy and I'm a consultant nephrologist, kidney specialist from Imperial NHS Trust.

Andrew 
Hello and I'm Andrew Frankel, a colleague of Jeremy's at Imperial College Healthcare NHS Trust, and welcome to For Kidney's Sake podcast and today's podcast entitled Hypertension and Chronic Kidney Disease. Now hypertension is bread and butter for primary care. However it is perceived as being a little more complex when it occurs alongside chronic kidney disease.

And today we really are delighted to be joined by Professor Ian Wilkinson, President of the British and Irish Hypertension Society, who is going to help us demystify and I hope simplify this area. Ian, thank you for joining us.

Ian
Thank you very much, it's a pleasure to be here with you.

Jeremy
So in as I said, we're going to try and explore a little bit the relationship between hypertension and chronic kidney disease, because although both are actually very common, we're not so good, I think, at joining the dots between the two and sort of leaving and treating them in isolation. And we also know that lots of our colleagues in primary care get very anxious when the two coexist. How should they be managed? What's the underlying cause? How should they treat it? So let's just start very simply. Is there a relationship or what is the relationship between hypertension and chronic kidney disease.

Ian
Yeah, you're right. They often coexist and they have a sort of bi-directional relationship. And what I mean by that is that kidney disease can cause high blood pressure and high blood pressure can cause kidney disease. And particularly once you've got kidney disease, high blood pressure is an important driver of a decline in renal function over time. So why that relationship is complicated is because the kidney is pivotal in controlling blood pressure.

And therefore when the kidney function starts to decline, there are a number of mechanisms like fluid retention, volume expansion, and activation of the renalgitantin system that help to drive blood pressure and keep blood pressure up. So each condition sort of reinforces the other.

Andrew 
So in practice, if you're in primary care and you see one, you should also be thinking about the other.

Jeremy
Yeah, and Andrew, you're right. And the danger is that when we treat hypertension just as the number, you know, 160 over 80, rather than thinking about it as doing damage, we miss the fact that there's damage going on to organs such as the kidneys.

Ian
Yeah, that's right. I mean, I think we shouldn't think about these things in isolation. We should always be looking at both of them.

Jeremy
Okay, so bringing this back to primary care, when someone is newly diagnosed with hypertension, what should clinicians be considering from the kidney perspective?

Ian
So think there are a couple of things. The first thing is could there be a renal cause for the hypertension? And secondly, has the hypertension already started to cause renal damage? So most people, about 90 % of people with high blood pressure, it's what we call primary or essential hypertension, which means we don't give a cause for it.

But it's important not to miss those 10 % that have a secondary cause because potentially we could do something about it. And things that make you think about a secondary cause include young people, patients with resistant hypertension, a sudden deterioration in blood pressure control, or for that matter, kidney function, and any abnormalities of serum creatinine or urine testing. And equally, it's important that we identify early damage to the kidney and that's where tests like creatinine EGFR and urine ACR are important to do.

Andrew 
So that's really helpful, Ian, and for primary care just thinking about those red flags that make you think that this could be secondary and the importance of doing the kidney health check in people with hypertension, both at diagnosis and subsequently. So very practical and very easy to do in primary care.

Jeremy
Yeah, that's right Andrew. I'm just thinking about the kidney function, the creatinine EGFR, the urinary acr are very important. So is the kidney driving the hypertension? Is the hypertension causing any kidney damage?

Andrew 
and let's just I mean I think I know the answer to this 'cause I think we've been going on about this in so many of our podcasts, but Ian, from your point of view, what should every patient with hypertension have in terms of baseline kidney assessment?

Ian
Well they all need a U and E as in creatinine doing, because that will allow us to estimate their GFR. And it's important that we do an ACR as well. I think urine dip can also be helpful, particularly in picking up potential secondary causes. And I think the reason these tests are important is because albuminuria and a raised ACR are often the earliest marker of kidney damage before the EGFR starts to fall.

Jeremy (05:03)
That's really important. I'm delighted you said that it did not me we banged on about this earlier These are separate tests of kiddies aren't they the urine ACR and the EGFR can tell different things that one can be abnormal when the others not and they're important to separate markers of kidney damage and I'm gonna reinforce the other thing you said which I always say all the time the urine dip is it's sort of equally important people might have a bit of blood and very low-level protein in their urine and that's different from just having a bit of proudness it's pointing out there may be more inflammation and other issues. So even though it's often quite hard in primary care, we really do want a urine dipstick and not just the ACR and that's really, really important because if it's just hypertension causing some kidney damage very early, there really shouldn't be, should not be blood and protein in the urine. There might be a slight bit of protein, sorry, because of a little bit of glomerular damage and early rise in ACR, but blood and protein is pointing us towards more inflammation in the glomerulus and that's not usually hypertension by itself. There's a primary kidney disease. So we talk about that a lot. I'm delighted that you raised it, not me. So we've done the baseline tests. We've got hypertension. We may or may not have some early kidney damage. How often should we monitor or how should we monitor kidney function in the presence of hypertension?

Ian
So, I think for most people with hypertension, we're going to do the eGFR and ACR perhaps every year. There are some people who've got higher risk, perhaps people who've already got a reduced GFR, or those people with diabetes perhaps, in which case you might want to do it every six months or so. Or occasionally we might do it more often than that. And sometimes we start drugs that can affect kidney function.

ACE inhibitors diuretics, and we probably want to check kidney function after two to four weeks of that initiation of those drugs.

Jeremy
That's really helpful. And you're right. It's not the hypertension itself. It's all those other things happening in the background. It's the trajectory of change prior to starting medicines and at the time you start them. And it's the level of kidney function when you're using or starting these drugs, isn't it? It's not just the one-off reading of blood pressure that determines how often to monitor things.

Ian
Yeah, that's absolutely right.

Andrew 
So Ian, let's now change the focus and let's just think a little bit about how the presence of kidney damage or CKD influences treatment decisions in a person with hypertension.

Ian 
So, if the two are together, what we're trying to do is lower the blood pressure but protect the kidneys. So that might change our choice of drugs and it should change our choice of drugs. So what we know in people who've got renal disease is that we want to be using ACE inhibitors or angiotensin receptor blockers, sartans, because they're particularly effective in patients who've got albuminuria, they reduce intramural pressure, they're known to reduce proteinuria, and they slow that progression of kidney disease, which is what we really want to be doing.

Andrew 
Absolutely.

And I think this is where we sometimes undersell these drugs. They're often sold to patients purely as antihypertensives, rather than what they are, which is disease modifying treatments. And not only do they slow progression of kidney disease, they reduce deaths too in patients with kidney disease, hypertension and of course heart failure. And the other reason these drugs often are viewed incorrectly is because they are also labelled

And this is true in the BNF or used to be as nephrotoxic.

Jeremy 
And that's a really important point, Andrew. We get lots of patients, don't we? You get very concerned. They either read the drug leaflet or they've Googled it and they get told these drugs should be avoided in kidney disease. And that stems back to that story about renal artery stenosis. But it's a real problem. And it causes confusion for patients who say, you know, the packet says caution in people with kidney disease. And yet here we are, we're banging on about these being the most important drugs for people with kidney disease. So the language is really important.

And I mean you and I do this all the time but we've really got to try and persuade colleagues not to say that ACE's and ARBS are nephrotoxic they're not they're nephroprotective

But there are some circumstances when we pause or hold them. But that's a really important issue. And the other issue that we should touch on with Ian now as well is about dose, because because they're so protective for kidneys, we don't just want people to be on one point two five milligrams of ram rapil, do we? We want really to have an optimised dose because the kidney really benefits from maximal renin and intensive blockade, even if the blood pressure seems reasonably well controlled. That's certainly our view. But Ian, I don't know if you'd agree with that.

Ian 
Yeah, I agree. We should be using reasonable doses of these drugs and they are protecting the kidney. So it's really important that we introduce them. As you said, even if the blood pressure is at target.

Andrew 
So what about the other drugs for hypertension? We know that diuretics and I was always taught this work well with inhibitors of the reninangitensin system. But once a patient has chronic kidney disease, primary care clinicians are often reticent about using diuretics. I think it's important that you comment on this and particularly about thiazides, which happens to be a class of drugs that I still use relatively frequently.

Ian (10:20)
Yeah,

I mean, I think as we were talking about with ACE inhibitors, it's become ingrained in the literature that thalazides are ineffective in people with renal impairment. And we now know that's simply not true. In fact, we knew that wasn't true in the 1970s. It's taken a long time for practice to change. These are effective drugs down to quite low levels of EGFR and probably stage four kidney disease as well. And they're effective at reducing blood pressure in those patients. So we should be using them because as you said, they work really well with blockers of the rene-adjusted system like ACE Inhibitors

Jeremy 
So delighted you said they and I agree with Andrew. think these are underused in primary care. And again, people get frightened that diuretics because they're making the kidneys, you know, pee more somehow nephrotoxic. And even though we might see a slight rise in creatinine a slight drop in GFR, actually, that's not detrimental. Clearly needs monitoring. But these are very, very effective in combination with ACEs and ARBs for treating blood pressure in chronic kidney disease. Do you have any comments about the choice of size? We moved to using a lot of in-depth in the UK as a thiazide but all those big actually quite recent studies in chronic kidney disease which are often worldwide have often used some chlorphalidone or bendrofluazide does it matter which of these thiazides we might use?

Ian 
I think it probably does. So, chlorothaladone has by far the most evidence across the board and it's my choice of thalazide diuretic. If you can't use it or don't want to use it, then endapamide is a reasonable alternative. It has less evidence, but it has some evidence.

Hydrochlorothiazide, which is often in combination pills, we shouldn't really be using chronically. It's got a black triangle against it because there's an increased risk of skin cancer. And bendroflorozide, really the meta-analysis show it's less effective. So it's commonly prescribed still, but we shouldn't be using it. So chlorothaladone should be your go-to drug.

Jeremy 
OK. And Ian so that was that was really helpful. And actually, that's going to change my practice because I suspect I've not been using enough calythalodone. So I need to reset my brain for calythalodone. But in your opinion,

What would be our second choice if we're treating hypertension in the setting of chronic kidney disease and we've all agreed we're going to start an ACE and ARB as a first line agent. Blood pressure is not yet less than 130 systolic and we want to add a second agent. Should we go for a calcium antagonist or a diuretic in somebody with early chronic kidney disease? What would be your advice? And let's ignore for the moment other comorbidities because, of course, there may be other drivers to a particular drug.

Ian 
Yeah, that's absolutely right. So in general, I'd add in chlorothaladone. If you can't or don't want to do that, then calcium channel blockers, dihydropyridines would be my choice. And within that class, it's really important that we choose long acting drugs. And the longest acting...

Diodeperidine and amlodipine also has lot of evidence of benefit. So long acting drugs produce stable blood pressure because you get stable steady state levels of the drug. And it also means if the patient forgets to take a drug dose, and we all do that all the time, then it doesn't affect the blood pressure very much. So we should also think about half lives of drugs because it's really important in achieving stable and good blood pressure control.

Jeremy 
Again, that's really helpful Ian. And OK, so amlodipine and Andrew and I have had a

Andrew 
Revive.

Jeremy 
bit of a discussion in the past about the dihydropyridine versus the non-dihydropyridine. So that's amlodipine versus verapamil and diltizem. There used to be bit of evidence about proteinuria, but actually Andrew keeps trying to persuade me that amlodipine really is better because it's longer acting and better for blood pressure. What are your thoughts about that?

Ian 
Yeah, I mean, it is longer acting. It's also better tolerated in general. So I think the world's moved, as you said, it's moved slightly more to dihydropyridines. And in all hats, we know Amlodipine was equally effective in reducing heart attack, heart failure. So that's why I would recommend it really.

Jeremy
And I think we should remind people isn't it that that all of these drugs it particularly in the setting of chronic kidney disease people need sort of good advice about sick day guidance so that if they get fevers, diarrhea, vomiting when they might be volume depleted especially pull their blood pressure lowering drugs for a few days but then resume them when they get better so this is just a temporary pause because we don't want lower blood pressure when you're already sick and and that's going to be important and it's really important in the setting of chronic kidney disease and I was assuming that you're going to agree with that and then targets you know what would you think about in the setting of chronic kidney disease targets for blood pressure Ian?

Ian 
Yeah, So I think we've moved on now, and what we're saying is...

Everyone should really have a target less than 130/80. And there's very good evidence for that now. But of course, we need to think about individual patients. So sometimes you might have a multiple comorbidities or very frail patient, and that might make you pick a slightly higher target. Equally, a young person, you may pick a lower target because we know that normal young people have really quite low blood pressures. So you think about individualising it. And I think your point about sick day rules is important. This isn't like type one diabetes and insulin. You don't need to take it if your blood pressure is low and you're ill. Yeah, so you're quite right.

Andrew 
So very important that primary care clinicians understand that there's clinical judgment involved in assessing targets and although we should be generally trying to get to less than 130 over 80, we might need to adjust that. Now before I mean this has been a fabulous podcast because as Jeremy says I've definitely learned a fair amount from it and will be changing a little bit of my practice. But before we finish, of course there's a fundamental here.

Which is measuring blood pressure. Ian, any comment on this? How do we do this?

Jeremy
Andrew, you've left the hardest thing till the end, actually. I mean, we've ignored that. we? All the way through this.

Andrew 
Yep.

Get it right.

Ian 
Yeah, so it's quite boring, but it's really quite important. so sit the patient down, make them rest for five, 10 minutes.

No chatting while you're making the measurements, no cross legs. Make sure the cuff's the right size for the arm. If you put a small cuff on a big arm, the pressure will be high artificially. And don't make a single reading. You need to make at least three and ignore the first reading. And actually, I've moved a lot more to getting patients to do their own blood pressure at home.

It's more accurate as what their real blood pressures like. And in some patients you might want to do 24 ambulatory blood pressure monitoring. It's a bit cumbersome and people don't really like it, but it has a use.

Jeremy 
So Ian, can ask you one last thing really before we close. We've talked about blood pressure and of course blood pressure is a physiological marker and we haven't had time to really explore the drivers to hypertension but actually that is really important isn't it? Poor diet, high in salt, heavy alcohol intake, obesity but we shouldn't just think about blood pressure as a number should we? We do need to think about underlying causes other than kidney disease.

Ian 
Yeah,

I mean...

I said 90 % of hypertension is essential, but I think we've been kidding ourselves really because we know that it's a complicated interaction between genes which are permissive and the environment. And you've hit on some of those environmental triggers. least 60 % of hypertension is driven by excess salt intake or being overweight. And reducing salt and cutting your weight down to the normal BMI range definitely help reduce blood pressure, as will reducing alcohol intake. And treating sleep apnea. The final point I want to make is tablet adherence is really important.

So we know that about half of the people who are not at target don't take some or all of their tablets. Part of that is misunderstandings like we were talking about, about what's good for you or not good for you. And part of it is patients who take a lot of tablets sometimes just forget. You know, it's human nature. So combination pills can help improve adherence and there's good evidence around that now.

Andrew 
I really do hope that in the UK we start seeing more of those combination pills because I know they do a lot more of them if you go outside the UK and they will help patients as we're actually identifying even more treatments for kidney disease. So Ian, incredibly practical for primary care, very relevant for primary care. I'm now going to ask you for your key takeaways that you want to give primary care.

Jeremy 
and you're only allowed three in.

Ian 
Three, right, okay. So one, hypertension and kidney disease are closely related and influence each other. When you're assessing a patient with blood pressure, it's important to also assess the kidney function with EGFR, ACR, and dip the urine, and we probably should be doing that every year as a minimum.

And when we think about treatments, we need to protect the kidney as well as lowering the blood pressure. And renal agitations system blocking drugs like ACE inhibitors should be our first line in doing that. And we should be getting people under 130, 80 to protect them from a heart attack stroke point of view, but also to protect the kidneys.

Jeremy 
Brilliant and thank you very much, but I'm just feeling upset that we didn't let him do three takeaways Andrew Did you want to add anything to that?

Andrew
Well, I I normally do this but I think Ian's given some fabulous takeaways. But that doesn't stop me, of course, highlighting just think kidneys in every patient with hypertension. As you said, don't forget that albuminuria is often the earliest sign of kidney damage and should be measured in association with urine dip. And we all need to learn to do blood pressure measurement properly, not in a rushed fashion.

Jeremy 
That's been really good. Ian, thank you so much for joining us. I've really enjoyed this. I've learned something. It's been really helpful.

Ian 
Thank you very much.